Lubricant



Patented Dec. 2, 1952 LUBRICANT -William T. Stewart, El Cerrito, and Alfred Goldschmidt, Oakland, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Application December 16, 1950, Serial No. 201,256

12 Claims.

The present invention relates to the preparation of novel and useful lubricating oil compositions. More particularly, the invention has to do with the preparation of lubricating oil com positions comprising mineral oil, polyalkylene glycol polymeric material, and a specified polar liquid compound, whereby the miscibility characteristics of blends of mineral oil and polyoxyalkylene polymeric material are substantially improved.

Polyalkylene glycol polymeric mixtures having the structural configuration wherein n is an integer greater than one and the free valances may be satisfied with hydrogen atom and/or organic radicals, such as methyl, ethyl, propyl radicals, etc., have hitherto been proposed as synthetic lubricants. terials may be prepared from ethylene oxide, and the higher 1,2-epoxides, such as 1,2-propylene oxide, the butylene oxides, mixtures of these materials, and the corresponding glycols. As known in the art, the resulting products may be polyoxyalkylene diols or polyalkylene glycol derivatives, in which one or both of the terminal hydroxyl groups have been removed during the polymerization reaction or subsequently thereto, as by etherification or esterification to yield monoor di-ether or monoor di-ester groups or a combination of such terminal groups whereby certain desirable properties are imparted to the final polymeric mixture.

By way of illustration, U. S. Patent 2,448,664 describes the preparation of a polyoxypropylene polymeric mixture according to the equation ROH ..(OO2H3.CH3) R.(OGQH3.CHa),-OH Monohydric 1, Z-prqpylene Polyoxypropylene alcohol oxide monchydroxy compound These products have molecular weights ranging from about 400 to 2,000 and higher, and are alleged to be useful as synthetic lubricants.

More recently polyoxyalkylene polymeric and copolymeric mixtures containing polymer units having more than two carbon atoms separating oxygen atoms in the polymer chain have been prepared and described. For example, U. S. Patent 2,520,733 describes the preparation of polymers and copolymers derived from trimethylene-glycol.

The foregoing compounds, as well as additional polymeric materials contemplated by the invention, are further described in U. S. Patent 2,491,432.

These ma- As compared with mineral oils, the polyalkylene glycols possess certain superior properties, as a result of which they would be more extensively used but for their high cost. For example, the polyalkylene glycols have higher viscosity indices, and lower pour points than mineral oils f comparable viscosity. A further additional property is that upon oxidation they tend to decompose into harmless volatile materials rather than to form complex insoluble engine deposits, their use in engine lubricating thus resulting in greater engine cleanliness.

It is also known that in general additives conventionally employed in combination with a mineral oil to improve one or more properties thereof, such as oxidation and corrosion inhibitors, detergents, and the like, are often without effect when combined with the polyalkylene glycol polymers. Another disadvantage of polyalkylene glycol polymeric materials is their limited solubility in mineral oils. At relatively high temperatures, blends of mineral oil and polyalkylene glycol polymer show phase separation.

Notwithstanding the poor miscibility characteristics of blends of polyalkylene glycol polymeric material and mineral oil, the blends are capable of manifesting the desirable properties of the polymers. Moreover, certain conventional mineral oil additives have been found desirably to affect the polymer when incorporated in the polymeric material in the presence of mineral oil. For a number of reasons, therefore, and for the further reason of economy, it is desirable to form blends of mineral oil and polyalkylene glycol polymeric material having improved miscibility characteristics.

Now, in accordance with the invention, it has been found that the miscibility characteristics of blends of mineral oil ,and polyalkylene glycol polymeric material can be improved substantially by the bringing together of mineral oil and polymeric material in the presence of a small amount of a polar solubilizing compound. More specifically, it has been found that the miscibility temperature, more fully hereinafter described, of mixtures or blends of mineral oil and polyalkylene glycol polymer can be considerably lowered by the incorporation in a blend or mixture of the aforesaid components of a small amount of a monohydric alcohol having more than four aliphatic carbon atoms in the molecule.

More particularly, the alcohols contemplated by the invention are alcohols containing more than four aliphatic carbon atoms in the molecule and free of polar substituents, such as amino or nitro radicals. These polar radicals, by imparting greater polarity to the alcohol molecule than it already possesses by virtue of the alcoholic hydroxyl group, adversely affect the alcohol in its function of solubilizing polymer and mineral oil. For this reason, such materials as polyhyd'ric alcohols and alkylolamines are to be avoided. On the other hand, such substituents, for example, a

benzene ring, which have little or no polarity, are

permitted.

In general, it has been found that the greater the number of aliphatic carbon atomsin the al- 'cohol molecule, the more pronounced the misci:

bility efiects imparted to the mixture of mineral oil and polymer. Therefore, alcohols having as many as 18, and more, carbon atoms in. the

molecule are suitable in carrying out the invention. It is pointed out, however, that since aromatic carbon, e. g., a benzene ring, contributes substantially no solubilizing effect to the alcohol 7) molecule; itis accordingly-ignored in determining the number of efi'ective carbon atoms in'the alcohol.

While thus far only alcohols have been described; and are preferred; the sulfur analogue of'the'. alcohols, namely, mercaptans, of similar definition, except that sulfur replaces oxygen therein, are not precluded from the broader aspects of theinvention'.

Specificexamplesof'suitable solubilizing agents are Z-ethylbutanol, 4-phenylbutanol, 4-methyl- 2-pentanol, di-n-propyl carbinol, l-methyl cyclohexanol-l, n-octanol, 2-ethylhexanol, 2-octanol, 3,5,5-trimethyl-l-hexan'ol, n-decanol, n-undecanol, 5-ethylnonanol-2, n-dodecanol, 2,6,8-trimethyl-@nonanol, 'l-ethyl-Z-methyl -undeoanol', 3,9-diethyl-6-tridecanol, 2(1,3,3',-trimethylbutyl) -5, 7,6-trimethyl-I-octanol, tert-octyl mercaptan, 'dodecyl'mercaptan, n-hexadecyl mercaptan.. The various isomers of'these alcohols canalso be employed;

It has been found that the amount of alcohol required tov effect an improvement in the miscibility characteristics of. polyalkylene. glycol .polymer and mineral oil blends is substantially independent of the proportions of. mineral oil. and polymer within a range of about 20 to about 80 by'volume of either component. That is, either component" can be present in the composition in an amountof about'one fourth to about fourfold the amount by'volume of" the other component, although for practical purposes an equal amount of eithercomponent is preferred. In generahthe amount of solubilizing alcohol can vary-from an amount of about 1% to'about'10% by volume of the finished composition, an amount of about 2% to 5% being preferred. While greater amounts than about 10% can be employed, such amounts are not particularly' desirablebecausethey adversely afiect' the properties-ofthe--finished composition, such as viscosity index.

In order to'obtain quantitative data on the effectiveness of the solubilizing agent to improve the miscibility of polymer and mineral oil, the following method and apparatus were employed: A. double-walled test tube, having an inside diameter of about 11 mm., an outside diameter of about 12 mm., and being about 9 cm. long, is provided with a cork stopper, and fitted with a thermometer. Suflicient sample is placed in the tube to cover the bulb of the thermometer (about 2cc.), after which the test tube with contents is placed in asuitable cooling 'bath, the contents of thetube being continuously sti'rred with the thermometer. Phase separation is manifested by a sudden cloud formation, and the temperature at which the cloud appears is noted, and recorded as the miscibility temperature.

The following examples. are given to illustrate compositions prepared in accordancewitlr the invention':

A mixture of polyalkylene glycol polymer ma- "terial and mineral oil was prepared by mixing equal parts, by volume, of the polymer and mineral oil. The polymer was prepared from 1,2- propylene'oxide and 2-ethylhexanol, and had a viscosity of'61.2 SSU at 210 F. The mineral oil wasv a; distillate cut obtained from naphthenic base crude, treated with aqueous phenol, sulfuric acid and percolated' through Fullers earth, and hada viscosity of 65.9 SSU at 210 F.

To portions of the foregoing mixture there was added separately the alcohols indicated below, the alcohol in all of the tabulated examples being added in anamountof "10 per cent, by-volume,

of the finished composition; 1 After the=incorpora-- tion ofthe alcoholthe miscibilitytemperature, as-

tabulated below, was noted and-recorded.

Miscib'ility Example Alcohol Teiny ielr ature,

None 2-Ethylbutanol Di-n-propyl carbinol.

i-Methylcyclohexanol n-Octanol 2-Ethylhexanol 2,6,8-trimethyl-4-nonan 7-Ethyl-2-methyl-4-undecauol 3,9-Dietl y-i-fi tridecauoli 2 (l 3 ,3 -trimethylbutyl)- 5 7 7 trlmcthyl-l potanol. Dodecyl mercaptan n-Hexadecyl inercaptan Octylphenoxy ethanol Z-N itro-2-methyl-3-hexanol 2-Amino-2-methyl-1 '-propanol r Example 23 A composition consisting-M80 volume percent ofthe polymer and 20 volume per cent of theoil employed inthe' examples tabulated above had' Example 24 To equal proportions, by volume, of the polymer employedin obtaining: the data tabulated'above, and of. a. mineral oil having a viscosity of 60.6 SSU at 210P-F. there was added 10' volume-per cent of- 3,9-diethyl-6-tridecanol; The blend of mineral. oil and polymer alone had a miscibility temperature of 123 F'., whereas the finished blend had a miscibility temperature of 50 F. The mineral oil in this example was derived'from a phenol, cresol. and propane treated residuum ofraniintermediate base crude to give a waxy raf'- finate. Theraffinate was-dewaxed by means-of methyl ethyl ketone, the dewaxed oil treatedwith clay and then fractionated to yield the finished oil.

Example 25 Example 26 A composition consisting of 45 volume per cent of the oil described in the example immediately above and 45 volume per cent of the 2-ethylhexanol initiated polymer employed in obtaining the tabulated data and volume per cent of heptadecanol had a miscibility temperature of 70 F.

Polymer and oil in equal proportions without the alcohol had a miscibility temperature of 0 F.

Example 27 A polymer was prepared from a mixture consisting of equal mol per cent proportions of ethylene oxide and 1,2-propylene oxide, employing octanol to initiate the polymerization reaction. The resulting polymer was esterified with acetic anhydride, the octanol-initiated ethylene oxidepropene oxide acetate polymer having a viscosity of 40.0 SSU at 210 F. Thi polymer was mixed with an equal volume of a mineral oil having a viscosity of 89.7 SSU at 210 F. and obtained from a. naphthenic crude distillate treated with aqueous phenol, sulfuric acid and clay. The blend of polymer and oil had a miscibility temperature of 8 F. Addition of 10 volume per cent 3,9-diethyl- 6-tridecanol resulted in a finished composition having a miscibility temperature of 45 F.

Example 28 A water-initiated polypropene oxide polymer having a viscosity of 62.0 SSU was blended with an equal amount of a spray oil having a viscosity of 36.6 SSU at 210 F. The miscibility temperature of the blend was 120 F. Addition of 10% by volume of the blend of 3,9-diethyl-6-tridecanol resulted in a composition having a miscibility temperature of l8 F.

Example 29 A polymer was prepared from stoichiometric proportions of ethylene oxide and isobutylene oxide, employing 2-butanol to initiate the polymerization reaction, the polymer being subse quently esterified with acetic anhydride to yield a product having a viscosity of 68.6 SSU at 210 F. Equal proportions of this polymer with the oil used in the tabulated examples gave a composition having a miscibility temperature of 82 F.

Addition of 10% by volume of the blend of 3,9-diethyl-G-tridecanol resulted in a composition having a miscibility temperature of 20 F.

As indicated in the foregoing examples, the mineral oil can be any hydrocarbon oil of lubricating oil viscosity. It can be a straight mineral oil or a distillate derived from parafiinic, naphthenic, asphaltic or mixed base crudes. Moreover, the oil may be one refined by conventional methods, such as solventor acid-treated oils or mixtures thereof. Also satisfactory for purposes of th present invention are synthetic oil such as those derived from the polymerization of olefins or the Fischer-Tropsch process. Various blended oils are also contemplated by the invention.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. Lubricating oil composition a major proportion of a blend of hydrocarbon oil and polyalkylene glycol polymeric material of lubricating oil viscosit in an amount, by volume, of about one-fourth to about four-fold the amount of said hydrocarbon oil, and a minor amount, sufficient substantially to lower the miscibility temperature of said blend, of a solubilizing agent selected from the group consisting of monohydric alcohols and monothiol mercaptans, said solubilizing agent having more than four aliphatic carbon atoms, being free of polar substituents, and being soluble in said blend at the miscibility temperature of said blend.

2. Composition substantially as described in claim 1, wherein the hydrocarbon oil is mineral oil.

3. Composition substantially as described in claim 2, wherein the solubilizing agent is a monohydric alcohol.

4. Composition substantially as described in claim 2, wherein the solubilizing agent is a monothiol mercaptan.

5. Composition substantially as described in claim 1, wherein the polyalkylene glycol polymeric material is a 1,2-polyalkylene glycol polymeric material having at least one terminal group selected from the class consisting of ether and ester groups.

6. Composition substantially as described in claim 5, wherein the solubilizing agent is a monohydric alcohol.

7. Composition substantially as described in claim 5, wherein the solubilizing agent is a monothiol mercaptan.

8. As a composition of matter, a blend of mineral lubricating oil and 1,2-polypropylene glycol polymeric material of lubricating oil viscosity in an amount, by volume, of about one-fourth to about four-fold the amount of said mineral oil, said blend containing in addition a minor amount, sufiicient substantially to lower the miscibility temperature of said blend, of a solubilizing agent selected from the group consisting of monohydric alcohols and monothiol mercaptans, said solubilizing agent having more than four aliphatic carbon atoms, being free of polar substituents, and being soluble in said blend at the miscibility temperature of said blend.

9. Composition substantially as described in claim 8, wherein the 1,2-polypropylene glycol material has at least one terminal group selected from the class consisting of ether and ester groups.

10. Composition substantially as described in claim 9, wherein the 1,2-polypropylene glycol polymeric material has a terminal ether group.

11. Composition substantially as described in claim 10, wherein the solubilizing agent is a monohydric alcohol.

12. Composition substantially as described in 7 claim l0,:,wherei1rthe solubilizing agent-is a mon- Number othiol;mercmptan. 2,481,278 WILLIAIVL T. STEWART. 2,510,540 ALFRED GOLDSCHMIDT. 2,520,733 2,543,735

REFERENCES CITED UNITED STATES PATENTS Name Date Rogers-et a1 Aug. 27, 1946 Number N m ,Date Ballard et a1 Sept. 6, 1949 Ballard. et a1 June 6, 1950 Morris et a1 Aug. 29, 1950 Stewart et a1 Feb. 27, 1951 OTHER REFERENCES Ucon Fluids and Lubricants, Carbide and Carbon Chem. Corp., New York, N. Y., May 31, 1 1948,pgs. 14 and 15. 

1. LUBRICATING OIL COMPOSITION A MAJOR PROPORTION OF A BLEND OF HYDROCARBON OIL AND POLYALKYLENE GLYCOL POLYMERIC MATERIAL OF LUBRICATING OIL VISCOSITY IN AN AMOUNT, BY VOLUME, OF ABOUT ONE-FOURTH TO ABOUT FOUR-FOLD THE AMOUNT OF SAID HYDROCARBON OIL, AND A MINOR AMOUNT, SUFFICIENT SUBSTANTIALLY TO LOWER THE MISCIBILITY TEMPERATURE OF SAID BLEND, OF A SOLUBILIZING AGENT SELECTED FROM THE GROUP CONSISTING OF MONOHYDRIC ALCOHOLS AND MONOTHIOL MERCAPTANS, SAID SOLUBILIZING AGENT HAVING MORE THAN FOUR ALIPHATIC CARBON ATOMS, BEING FREE OF POLAR SUBSTITUENTS, AND BEING SOLUBLE IN SAID BLEND AT THE MISCIBILITY TEMPERATURE OF SAID BLEND. 